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A173891
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Numbers n such that the n-th noncomposite number plus the (n+2)nd noncomposite number is an even semiprime.
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1
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1, 3, 16, 37, 40, 47, 55, 56, 74, 103, 108, 111, 119, 130, 161, 165, 185, 188, 195, 200, 219, 240, 272, 273, 292, 340, 359, 388, 420, 427, 465, 466, 509, 521, 554, 600, 606, 622, 630, 634, 668, 683, 684, 703, 710, 711, 734, 762, 792, 814, 822, 823, 830, 831
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OFFSET
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1,2
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COMMENTS
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LINKS
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FORMULA
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prime(a(n+1)-1) = n-th balanced prime.
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MAPLE
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A008578 := proc(n) if n = 1 then 1; else ithprime(n-1) ; end if; end proc: for n from 1 to 1000 do sp := A008578(n)+A008578(n+2) ; if type(sp, 'even') and numtheory[bigomega](sp) = 2 then printf("%d, ", n) ; end if; end do: # R. J. Mathar, Apr 25 2010
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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All but one value shifted by 1, and missing values (40, 634, 762) inserted, by R. J. Mathar, Apr 25 2010
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STATUS
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approved
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